Practice question

MCQ

Question

The energy of an electron in the first orbit of He⁺ is -54.4 eV. What is the wavelength of the photon emitted when the electron transitions from n = 4 to n = 2 in He⁺? (h = 6.626 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m s⁻¹, 1 eV = 1.6 × 10⁻¹⁹ J)

Options

Choose one · Correct answer highlighted

121.7 nm Correct 486.1 nm 30.4 nm 164.0 nm

Explanation

ΔE = 10.2 eV. λ = hc/ΔE ≈ 121.7 nm.

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